Advanced Calculations for Defects in Materials: Electronic Structure Methods

This book investigates the possible ways of improvement by applying more sophisticated electronic structure methods as well as corrections and alternatives to the supercell model. In particular, the merits of hybrid and screened functionals, as well as of the +U methods (orbital dependent intraatomic correlation correction) are assessed in comparison to various perturbative (GW) and Quantum Monte Carlo (QMC) many body theories, as well as to experiment. The inclusion of excitonic effects is also discussed by way of solving the Bethe-Salpeter equation or by using time-dependent DFT TD-DFT), based on GW or hybrid functional calculations. From this comparison a clear picture emerges regarding the connections and boundaries between these methods, as well as about the broad criteria determining the choice between them for a given problem.
Particular attention is paid also to overcome the side effects connected to finite size modelling. The reader will find various correction schemes for the supercell model, the description of alternatives by applying embedding techniques, as well as algorithmic improvements allowing to treat an ever larger number of atoms at high level of sophistication.